Centrifugal separator



1970 H. w. THYLEFORS 3,494,544

CENTRIFUGAL SEPARATOR Filed April 50, 1968 INVENTOR. lyfl'flt 010950! 7! 2288514 United States Patent Office 3,494,544 Patented Feb. 10, 1970 3,494,544 CENTRIFUGAL SEPARATOR Henric Wilhelm Thylefors, Stockholm, Sweden, assignor to Alta-Laval AB, Tumba, Sweden, a corporation of Sweden Filed Apr. 30, 1968, Ser; No. 725,446 Claims priority, application Sweden, May 10, 1967, 6,517/67 Int. Cl. B04b 11/04 US. Cl. 233-19 7 Claims ABSTRACT OF THE DISCLOSURE The present invention relates to a centrifugal separator of the type having channels extending radially inward from the sludge space of the rotor to a receiving chamber provided with an outlet for separated sludge.

A separator of this type is shown in Swedish patent specification No. 173,711. This separator, which can be used, for example, to separate a yeast concentrate from a yeast suspension, has a paring means displaceable in a radial direction in the receiving chamber. When the paring edge of the paring means is displaced radially inward, the strength of the pared yeast concentrate is increased. This increase, of course, results in an increase of the viscosity of the yeast concentrate. However, the pressure drop which forces the yeast concentrate into the paring chamber is decreased due to the radially inward displacement of the paring edge, despite the fact that the increased viscosity requires an increased pressure drop so as to counteract the increased flow resistance. This situation entails the risk of clogging the channels and consequently involves difficulties in obtaining a yeast concentrate of uniform and high strength.

The present invention eliminates this difiiculty by providing means for closing and opening the channel openings into the receiving chamber, such means being actuated to uncover these openings only after the sludge con centrate in the sludge space has reached the desired strength. Thus, the pressure drop which forces the sludge concentrate inwardly to the outlet of the receiving chamber can be kept large as well as constant, since it is not necessary to displace the outlet opening in order to control the concentration.

The closing and opening means may be in the form of pistons driven hydraulically and movable in a radial direction.Preferably, however, the invention includes such means in a form which is not loaded in the closing or opening. direction. The closing and opening means can be a disc of which the edge forms the closing surfaces, and which is movable in the axial direction.

So that the mobility of the discwill not be impaired by a higher hydraulic pressure formed at one side of the disc, communications are provided between both sides of the disc. These communications may, of course, be constituted by grooves at the inside of the paring chamber. However, they are preferably constituted by one or more openings provided in the radially outer parts of the disc.

Alternatively, the disc can be designed as a rim with spokes.

Preferably, the desired strength of the sludge concentrate is kept constant by controlling the opening frequency of the closing and opening means, and the duration of the opening period is kept at a predetermined constant value, for example, one or more seconds. Frequency controllers filling these requirements are generally known and of different types.

The means actuating the closing and opening means can be driven hydraulically, pneumatically or electromagnetically.

Automatic control of the strength of the sludge concentrate can be obtained by inserting in the outlet from the receiving chamber a meter sensitive to changes in the concentration of the sludge, for example, a viscosity meter, and arranging for this meter to actuate the closing means, preferably via a frequency controlling means. Consequently, in the latter case the meter does not directly determine the point .of time for the next opening but determines the frequency with which the closing and opening means are operated.

In one embodiment of the invention, which has been found suitable, the outlet from the receiving chamber is formed by a paring means.

The invention is explained more in detail below with reference to the accompanying drawing, in which the single illustration is an axial sectional view of one embodiment of the new separator.

Referring to the drawing, a centrifugal rotor 1 has a cover 2 secured to the rotor by a locking ring 3. The rotor is mounted on and driven by a hollow spindle 5 and has a separating chamber containing a conical disc set 6, the rotor also having a distributor 7 with radial vanes 8. The stationary pipe for supplying the liquid to be separated is shown at 9. The outlet for separated liquid is formed by a paring chamber 10 containing a stationary paring disc 11 with a paring channel 12. At the rotor bottom is a paring chamber 13 having a stationary paring tube 14 inserted therein. Spaced around the rotor axis are bent pipes, one of which is shown at 15, extending from the sludge space 16 radially inward to the paring chamber 13. In the latter is a disc 17 having a peripheral edge which, in the position shown in the drawing, closes the openings of the pipes 15 into the chamber 13. The disc 17 is provided along its periphery with openngs 18 located between the openngs of the pipes 15 and which allow communication between the spaces above and below the disc 17. A spring 19 presses the disc 17 upward against abutments formed by the heads of three bolts, one of which is shown at 20, screwed to the rotor bottom. A spindle 21 secured to the disc 17 is provided at its lower end with a magnet core 22 which, when attracted by energization of a magnet coil 23, pulls the spindle and consequently the disc 17 downward until the latter strikes against the top of the spindle 5. The paring tube 14 is connected to an outlet pipe-line 24 for the sludge concentrate.

In describing the operation of the separator, it will be assumed as an example that a yeast suspension is to be separated. The latter, which can have any arbitrary yeast concentration, is supplied through the pipe-line 9 and flows through the distributor 7 outward into the separating chamber outside the disc set 6. Clean separated liquid flows from the inner edges of the disc set into the paring chamber 10 and is discharged from the latter by means of the paring disc 11. Separated yeast is collected in the sludge space 16. The concentration of the yeast in the sludge space increases as the period of time between the sludge discharges increases, but decreases as the opening (discharge) periods of time increase. Thus, the yeast concentration can be controlled by means of these two factors of time. The operation is usually such that the opening period of time is kept constant and the period of time between the openings is controlled. In the present case, it is assumed that a viscosity meter 26 is inserted in the pipe-line 24. This meter has an operative connection 27 to a controller 28 for regulating the frequency with which current is supplied to the magnet coil 23 through conductors 29. Consequently, under constant conditions of operation the disc 17 will uncover the openings of the pipes 15 With a certain frequency, and the yeast concentrate discharged by the paring tube 14 will have a strength corresponding to this frequency. If the viscosity meter 26 senses an increased viscosity of the yeast concentrate, the meter adjusts the frequency controller 28 to provide an increased frequency, whereby the yeast discharges take place more often and the strength of the yeast concentrate is lowered, until the desired concentration is reached. If the sensed viscosity is decreased, this control takes place in the opposite manner.

It will be understood that the disc 17 constitutes means for closing and opening the openings of pipes 15 into the receiving chamber 13; and the parts 21, 22, 23 and 26 through 29 constitute means for actuating the disc 17 with an opening frequency determined by the viscosity of the concentrate discharging through pipeline 24.

Instead of the paring tube 14, the chamber 13 can have a number of outlets in the form of holes 25 in the rotor bottom. One of the holes is shown with dotted lines so as to indicate that it is an alternative of the paring means 14.

I claim:

1. In a centrifugal separator, the combination of a centrifugal rotor having a separating chamber provided with a peripheral sludge space and also having an inlet 1 to said chamber the rotor also having a receiving cham her and channels extending radially inward from the sludge space to the receiving chamber, said channels having openings into the receiving chamber, said receiving chamber having an outlet, and means for closing and opening said channel openings into the receiving chamber.

2. The combination according to claim 1, in which said closing and opening means include a disc having an edge which forms closing surfaces coacting with said channel openings.

3. The combination according to claim 2, in which the radially outer portion of said disc is provided with at least one opening to allow passage of sludge from one side of the disc to the other.

4. The combination according to claim 1, comprising also means for actuating said closing and opening means with a selected opening frequency.

5. The combination according to claim 4, in which said actuating means include an electromagnet.

6. The combination according to claim 1, comprising also a meter inserted in said outlet from the receiving chamber and responsive to changes in the concentration of sludge from said outlet, and an operative connection from said meter'to said opening and closing means for actuating said last means.

7. The combination according to claim 1, comprising also a paring means forming said outlet from the receiving chamber.

References Cited UNITED STATES PATENTS 2,955,754 10/1960 Nyrop 233-20 3,167,509 1/1965 Steinacker 233-19 3,272,430 9/1966 Thylefors 233-47 ROBERT W. JENKINS, Primary Examiner 

